Enhanced telephone services in both analog voice and data communications are presently available which support a broad range of applications in the same telecommunications network. The advent of services such as CALL WAITING, CALLING LINE IDENTIFICATION and CALL FORWARDING are examples of such services utilizing currently available digital technology. Combined with the widely acclaimed multimedia communications technology represented by the Internet and its interface, World Wide Web, there is also provided a convenient and effective access to the Internet's vast catalogue of resources.
Understandably, an ever increasing use of the Internet in residential and small business environments is accompanied by a corresponding increase in the use of dial-up access. However, the use of a public switched telephone network (PSTN) for dial-up Internet access is creating new challenges for public network providers as a result of increased call holding times and an inability of network subscribers to perform any telephony functions while connected to the Internet. As a result, there is a pronounced need for telephone service subscribers to have the capability of accepting and placing telephone calls from and to the PSTN while the subscriber's telephone line is in use for non-circuit-switched communications, namely for Internet access.
Heretofore, switching between analog telephony of a plain ordinary telephone service (POTS) common access network and the dial-up Internet was generally unavailable to the POTS user. However, equipment advances in modems that are switchable between voice and data modes provide limited service in point-to-point applications, but have no regard for effects at higher protocol layers. Although multiple dissimilar services over a common access infrastructure are available through dynamic bandwidth allocation as exists in integrated services digital network (ISDN) technology, the use of such is often prohibitively expensive, especially for a residential subscriber.
Alternatively, a need to use common access facilities can be achieved by acquiring an additional subscriber line, although both cost and unavailability may obviate this option.
Internet protocol (IP) telephony permits multiplexing both voice and data over common access facilities using IP. Solutions of this nature are limited, however, in five significant ways:
(1) The call must originate from or be received on an Internet-enabled personal computer (PC); PA1 (2) The Internet-enabled PC must be connected to the Internet to receive calls which must be transmitted through the Internet to be received; PA1 (3) Speech quality may be impaired, at least in part, in calls using the Internet as a transport mechanism due to the effects of latency, jitter and delay; PA1 (4) Internet-based calling currently requires either that calling parties know the Internet protocol (IP) address of the destination, requiring dialing a complex series of numbers via a telephone keypad, or that the system otherwise determine the appropriate IP address through a series of complicated lookups or through user IP address registration. In either event, existing subscribers require negotiations every time the IP address changes. A significant problem with IP address registration, moreover, is that many dial-up users have dynamically-assigned IP addresses. This means that a new address is assigned for every login by a user; and PA1 (5) Only calls that have been appropriately converted to Internet calls can be accepted which excludes traditional POTS analog calls when the line is in use.
Presently the prior art requires a POTS subscriber to tear-down their existing Internet connection before accepting a call. Two major disadvantages occur in this approach. Firstly, a current Internet session is permanently terminated. This would result in a lost IP address and lost traffic. Moreover, several attempts to reconnect may be required on a busy Internet Service Provider (ISP), together with an attendant loss of a physical port. Secondly, there is no provision for placing outgoing calls. Considering the investment of time and costs in establishing an Internet session, premature termination of the session merely to answer an incoming call, which may be unimportant, would be indeed regrettable. Furthermore, the inability to place an outgoing call while in an Internet session imposes a severe inconvenience on an Internet user.
Dual simultaneous voice and data (DSVD) modems are available which provide near toll-quality voice and data carried simultaneously between any two points employing the DSVD technology. However, this point-to-point approach does not allow the user to accept calls from the PSTN or place additional calls thereto while connected to the Internet.
A typical example of prior art is described in U.S. Pat. No. 5,287,401, Lin, issued Mar. 15, 1993 and entitled APPARATUS AND METHOD FOR A MODEM FOR DETECTING A CALL WAITING SIGNAL, which relies on existing call waiting signal detection and requires special detection circuitry within the modem for its operation. Additionally, no provisions are made for transmission time-outs which may occur at higher protocol layers. Furthermore, Lin requires a user to tear-down the modem connection to accept an incoming call, and makes no provision for placing outgoing calls.
Without providing specific apparatus for end-to-end signaling performance, the foregoing solutions will always be limited.